624 TESTING FOR BUTTERFAT 



Method II. Add 9 cc. of water after the cream has been 

 weighed into the test bottle and before the acid is added, then add 

 17.5 cc. acid and proceed as in previous method. This method is 

 applicable with the 9-gram bottle only. 



Method III. Add 8 to 12 cc. of acid in the case of the 9-gram 

 bottle or 14 to 17 cc. of acid in the case of the 18-gram bottle, or add 

 acid until the mixture of cream and acid, after shaking, has a choco- 

 late brown color. After the cream and acid have been thoroughly 

 mixed and all lumps have completely disappeared, add a few cubic 

 centimeters (not less than 5 c.c.) of hot, soft water, whirl five min- 

 utes, add hot, soft water to near top of scale and whirl one minute. 



The proper speed of the centrifuge is 800 revolutions per min- 



Figf. 99. Babcock Tester 

 Courtesy Davis-Watkins Dairymen's Mfg. Co. 



ute for an 18-inch diameter wheel and 1000 revolutions per minute 

 for a 12-inch diameter wheel. 



Reading the Cream Test. Place the test bottles into the water 

 bath and read after a temperature of 130 to 140 degrees F. has been 

 maintained for not less than three minutes. Just before reading the 

 test and when taking the bottles from the water bath, add a few 

 drops of glymol. The glymol removes the meniscus or curve on 

 top of the fat column, leaving a straight line which is sharply defined 

 and readily seen. 



Measure the fat column, preferably using dividers, and record 

 the percentage of fat on the test sheet, opposite the test bottle num- 

 ber of the respective patron. 



